What are some functions in PHP that can control output buffering and manage output content?

Output buffering in PHP is a mechanism that allows you to capture output generated by a script before it is sent to the browser. This can be useful for manipulating or modifying output content before it is displayed. PHP provides functions like ob_start() to start output buffering, ob_get_contents() to get the buffered output, ob_clean() to clean (erase) the buffer, and ob_end_flush() to flush (send) the buffer contents to the browser.

// Start output buffering
ob_start();

// Output some content
echo "Hello, World!";

// Get the buffered output
$output = ob_get_contents();

// Clean (erase) the buffer
ob_clean();

// Modify the output content
$output = str_replace("World", "PHP", $output);

// Send the modified output to the browser
echo $output;

// Flush the buffer
ob_end_flush();